Centering for and method of constructing arches.



No. 802,004. PATENTED OCT. 1-7, 1905.

D. B. LUTEN. GENTERING FOR AND METHOD OF OONSTRUUTING ARCHES.

APPLICATION FILED PEB.25,1905.

- 2 SHEETS-SHEET 1.

Wiiw e'mxeg No. 802,004. 0 PATENTED OUT. 17, 1905. D. B. LUTEN.

GENTERING FOR AND METHOD OF GONSTRUCTING ARCHBS. APPLICATION FILED PEB.25.1905.

2 SHEETS-SHEET 2.

DANIEL B. LUTEN, OF INDIANAPOLIS, INDIANA.

CENTERING FOR AND METHOD OF CONSTRUCTING ARCHES.

Specification of Letters Patent.

Patented Oct. 17, 1905.

Application filed February 25,1905. Serial No. M7306.

Zo (ti/l whom, it may concern.-

Beit known that I, DANIEL B. LUTEN, acitizen of the United States, residing at Indianapolis, Indiana, have invented certain new and useful Improvements in Centering for and Methods of Constructing Arches, of which the following is a specification.

My invention relates to the art of masonry arch construction, and pertains more particularly to a-new and improved construction of centering or false work for arches, involving also a novel method or process in the construction of the arch itself by reason of the novel character and manner of manipulating the centering or false work. In building arches of considerable span-say seventylive feet and upward engineers usually specify that the uprights of the wood en centers on which the arch is supported during construction shall be erected on wedges, which are removed grad ually after the arch is completed, so as to let the stresses develop in the arch ring gradually. Sand-boxes have also been used for this same purpose, theupright-supports resting in boxes of sand confined by means of removable plugs or the like, and when it is desired to lower the centers or strike the centers, as it is called, the plugs are withdrawn so as to let the sand run out of the boxes and the uprights settle slowly.

My present invention comprises a novel method and construction in arch-centering whereby this same result of aneasy and gradual settling of the arch-ring may be attained in asimpler and more economical manner than by the means and methods above described and which at the same time effects an economy in the cost of the centering itself. Generally describing the novel principle and feature of the present invention it may be stated that in the erection of arch-centering the uprights employed have heretofore. so

settlement of the arch-ring, my substitute for the latter residing in the expedient of gradually removing the sway-bracing after the archring has been completed to the point at which the centering may be removed, whereby the light uprights gradually bend or buckle, af- 6o fording sufiicient resistance to support the ring against the sudden imposition of its own weight effect, but' at the same time yielding sufficiently to permit the gradual settling to permanent form which every arch-ring undergoes upon the gradual withdrawal of the support afforded by the centering.

The principal of my invention is disclosed in the accompanying drawings, which show an arch-ring supported upon. my improved 7o centering and also illustrate the manner in which the stresses are allowed to develop gradually in the arch-ring upon the removal of the centering.

Referring to the drawings, Figure 1 is a side elevational view of an arch supported upon my improved centering. Fig. 2 is a cross-sectional view of the same on the line 2 2 of Fig. 1. Fig. 3 is a perspective fragmentary view in which the uprights are shown as having greater width than thickness with bracing required consequently only in the plane of the lesser dimension. Fig. 4 is a view similar to Fig. 2, illustrating the bending or buckling of the uprights during setef/j' tling of the arch and upon removal of the bracing. Fig. 5 is an elevational View of another form of centering in which the weight of the arch is transmitted to piling by compression-pieces radiating fromthe tops of the 0 Fig. 6 is a similar elevational view of aflat arch or girder in which still another arrangement of the compression-pieces is shown.

Referring to the drawings, 5 may designate the ring of a concrete or other masonry arch sucl1,for instance,as occurs in an arch-bridge- I 00 6 designating the spandrel-walls thereof.

7 designates the usual centers, supported on uprights 8, resting on sills or other firm supports 9. The uprights 8, which are usually oak or other wooden timbers, are intention- I05 ally of such cross-sectional dimensions proportionately to their length as to be incapable of resisting the gravity thrust of the archring without bending or buckling thereunder.

1O designates longitudinal, and 11 trans- I1 verse, sway-bracing whereby said uprights are supported at various points between their ends against bending or buckling either longitudinally or transversely of the arch. I

have found in practice that in the construction of an arch requiring oak uprights six inches square in cross-section to carry the load unbrace'd uprights four inches square in cross-section may be safely substituted when used in conjunction with sway-bracing to afford the same rigid support to the arch-ring during construction. When in the building of the arch the work has progressed to the point where the centering is to be removed and the arch-ring allowed to settle, l gradually remove the sway-bracing, the effect of which is to cause the light uprights under the heavy load to slowly bend or buckle a few inches out of true vertical posit-ion, as illustrated in Fig. 4. Preferably the bracing is removed gradually from the several uprights or columns, so that the settling of the archring thereupon takes places very gradually, the uprights acting as springs elastically supporting a large part of the weight, While at the same time permitting the arch to gradually assume its full loading. As the uprights bend their resistance to the imposed loading decreases, so that they act as springs supporting the arch, yet with'diminishing resistance as the arch settles, thus requiring the arch to assume its full loading as the uprights buckle. a most desirable function. If there be any danger of the collapse of the arch as the support of the centering decreases, it may be guarded against by the previous introduction of auxiliary props to receive the arch in case the centering should suffer complete collapse. After removal of the bracing from the uprights the uprights themselves may be cut out one by one, removing first, preferably, the more unimportant members near the ends of the span.

A'desirable modification for some cases is the use of compression members 8, Fig. 3, having a less diameter in one direction transverse to its length than in the other, so that buckling can occur in but one direction. The compression members are then braced against bending in this direction, as by the transverse braces 11, and the bracing in the other direction may be dispensed with.

Fig. 5 shows a form of centering embodying the principle of'my invention, wherein the weight of the arch is transmitted to piling 12 by compression members or struts 8 radiating from the tops of the piling, said compression members being designed to be flexible and held against bending during erection of the arch-ring by bracing 10 While I have described the device as applied particularly to the lowering of an arch, it is apparent that the principle of the invention is applicable to the construction of girders, floors, and other constructions where a superimposed structure is to assume the loading after erection on a temporary false work, as in Fig. 6, wherein 8 represents the main compression-struts braced against buckling by the braces 10.

In view of the fact that the heavy uprights constitute the most expensive part of the centering, while the sway-bracing represents the least expensive part thereof, it is obvious that my invention effects a material economy in the total cost of centering material, aside from the important advantage of dispensing with the necessity for wedges, sand boxes, and similar devices for effecting the gradual lowering of the uprights from the arch-ring in striking the centers.

I have used the term uprights not in the narrow sense of a vertical member, but in the broad sense of a vertical or inclined piece or any compression member or strut.

I claim- 1. The method of constructing an arch which consists in erecting the same on centering having braced uprights too light to carry the arch without bracing, and subsequently removing the bracing, allowing the uprights to bend or buckle as the arch settles and assumes its loading, substantially as described.

2. The method of constructing an arch which consists in erecting the same on centering having laterally braced uprights too light to carry the arch without bracing, and subsequently gradually removing the bracing from the uprights successively, allowing the latter to bend or buckle as the arch settles and assumes its loading, substantially as described.

3. In arch or analogous constructions. a false work or centering having flexible weightresisting members held rigidly to place by removable bracing, substantially as described.

4. In arch or analogous constructions, a false work or centering having flexible members adapted to resist endwise compressive strains held rigidly to place by removable lateral bracing, substantially as described.

5. An arch or similar centering comprising uprights or columns too light to alone carry the weight of the arch without bending, and removable sway-bracing for said uprights, substantially as described.

6. An arch or similar centering comprising uprights or columns too light to alone carry the weight of the arch without bending, and removable sway-bracing serving to support said uprights against bending in all directions, substantially as described.

Signed by me at Indianapolis, county of Marion, State of Indiana, in the presence of two witnesses.

DANIEL B. LUTEN. Witnesses:

A. C. BROWN, J. C. STUoTsENBERe. 

